1. Field of the Invention
The present invention relates to mine ventilation devices, and particularly to a mine stopping for blocking the flow of air through a passageway in a mine, the mine stopping being characterized by at least two panels connected by a hinge.
2. Description of the Related Art
Mine ventilation systems are designed to deliver fresh air to the working face of the mine, and to exhaust noxious gases, such as methane, from the working face. Typically fresh air will be forced into an intake passage by a blower motor and the oxygen depleted or contaminated air is exhausted through a return passage. When a second shaft or tunnel does not intersect the intake passage, a connecting passage or crosscut may be made to connect the intake passage with the return passage. As the working face of the mine is advanced, the original crosscut falls farther behind and the blower motor lacks sufficient pressure to drive the fresh air to the working face due to the loss of pressure through the crosscut. Consequently, it is necessary to make additional crosscuts near the working face of the mine, and to block the passage of air through the crosscuts closer to the entrance of the air intake passage.
Further, it is common to have one or more workrooms branch off the main working section, which are mined for short periods of time and then abandoned as the main tunnel is lengthened. It is often desirable to block the flow of air to the abandoned workrooms to maintain sufficient pressure in the main working section. A variety of temporary devices, such as line brattices or curtains, and permanent devices, including stoppings made from concrete blocks or metal, as well as overcasts and undercasts, have been developed for altering air flow through a mine to enhance the mine""s ventilation system. Permanent devices will often have a door disposed therein to provide an emergency exit in case of collapse of one of the passages, or to provide pressure release from concussive forces, such as blasting.
A number of patents describe temporary mine stoppings made from flexible materials, including U.S. Pat. No. 1,778,979, issued Oct. 21, 1930 to A. J. Lockhart (canvas curtain with wire about its periphery stapled to wooden plugs); U.S. Pat. No. 3,006,267, issued Oct. 31, 1961 (brattice of overlapping strips of jute or duck, permitting the passage of mine cars); U.S. Pat. No. 3,715,969, issued Feb. 13, 1973 to J. V. Burgess, Jr. (system for extending a line brattice); U.S. Pat. No. 3,863,554, issued Feb. 4, 1975 to N. A. Boyd (flexible sheet material with wire strap around its perimeter and novel frame members for compressing the strap against the mine opening); U.S. Pat. No. 4,770,086, issued Sep. 13, 1988 to J. C. Gabster (frame for extending a line curtain); and U.K. Patent No. 2,087,459 (parachute stopping tied to girders with skirt which unfurls to seal passage under pressure).
A permanent mine stopping (wall) is shown in U.S. Pat. No. Re. 34,220, issued Apr. 13, 1993 to Kennedy et al., being a reissue of U.S. Pat. No. 4,915,540, issued on Apr. 10, 1990. The patent describes a contractible mine stopping comprising a plurality of rows of blocks made from a noncompressible material and at least one row of blocks with is compressible. Three different embodiments of compressible blocks made from metal are shown. An overcast is disclosed in U.S. Pat. No. 5,466,187, issued Nov. 14, 1995 to Kennedy et al.
U.S. Pat. No. Re. 32,675, issued May 24, 1988 to Kennedy et al. The ""675 patent shows a mine stopping with extensible walls consisting of a plurality of extensible panels aligned side by side. Each extensible panel has upper and lower telescoping channels. The extensible panels are secured to horizontal bars by metal ties. The gaps between adjacent panels are covered by lap members and sealed with filler.
Mine stoppings with doors are shown in U.S. Pat. No. 752,955, issued Feb. 23, 1904 to W. Clifford (mine stopping having at least two swing doors operating in tandem to redirect air flow through three passages); U.S. Pat. No. 1,478,303, issued Dec. 18, 1923 to S. H. Snyder (wooden frame covered with canvas having spring biased door for pressure relief during blasting); U.S. Pat. No. 2,621,725, issued to A. Shacikoski (shuttle door for a mine car); U.S. Pat. No. 4,388,779, issued Jun. 21, 1983 to C. R. Peterson (door featuring easier opening across a pressure drop); and German Patent No. 4,102,331, published Jul. 30, 1992 (corrugated sheet metal lining underground passage with weather door fitted across passage).
The permanent mine stoppings described above are generally designed for disposition normal to the flow of air through the passage. U.S. Pat. No. 6,164,871, issued Dec. 26, 2000 to Kennedy et al., describes a mine stopping with a door shown as a truncated V-shape, with two walls angled from the ribs of the mine and a door normal to the flow of air joining the two angled walls. It is said that the angled walls may be constructed according to the method described in U.S. Pat. No. Re. 32,675, discussed above (col. 4, lines 54-60). However, the ""675 patent relied on horizontal bars extending between holes established in the ribs on opposite sides of the mine to support the extensible panels. Those horizontal bars are not shown in the ""871 patent, and the patent does not disclose what adaptation is made to support the extensible panels. It will be noted that Kennedy does not show a hinge joining the angled walls to the door.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a hinged mine stopping solving the aforementioned problems is desired.
The hinged mine stopping has at least two panels joined by a hinge defining a wall adapted for forming an air tight seal in a mine passageway to improve mine ventilation. Each panel has a lower section defined by a sheet of gas impermeable material mounted on a tubular, rectangular frame, and an upper section defined by a sheet of gas impermeable material mounted on a tubular, inverted U-shaped frame. The side members of the upper section frame telescope into the side members of the lower section frame for height adjustment of the panels. Preferably the hinged mine stopping is disposed between the ribs of a mine in a V-shape, with the apex directed towards the high pressure side to reduce the load on the stopping, the perimeter of the stopping being sealed.
The sheet material is preferably metal, particularly steel, but may be formed from a lightweight concrete or composite treated with a flameproof sealant. The sheet material may be flat, but the mine stopping can resist greater pressure if the sheets are made from corrugated material.
The hinge is disposed between the lower section of adjacent panels. The hinge may be a strap hinge composed of an elongated flexible metal strap welded to the frame side members of both panels. Alternatively, the hinge may be a plurality of ordinary door hinges attached to the frame side members. In the latter case, the hinged joint may be sealed by an elongated metal strip on the outside of the joint retained by a brace inside the joint.
The telescoping sections are locked at the desired height by either all thread bolts or friction bolts extending between the upper frame members of the upper and lower sections. The upper section sheet is disposed to form a friction fit against the lower section sheet material so that no seal is needed between the upper and lower sections. The mine stopping is held in place vertically by tension between the upper and lower sections maintained by the lock bolts, and horizontally by metal straps or tabs nailed to the ribs of the mine. The perimeter is sealed by expandable metal shims or wedges and conventional fiber filler.
Advantageously, the mine stopping may be folded compactly with one panel overlying the other for transport into the mine with the sealing material disposed between the panel. The low profile package permits up to eight stoppings to be hauled on a mine car, as compared to two block stoppings.
The hinged mine stopping may be installed faster, resulting in an a more efficient and economical use of labor. It is estimated that the hinged mine stopping would require about fifteen minutes to install, as compared to four hours for a block stopping and about forty-five minutes for the extensible panel stopping of the ""675 Kennedy patent. In mining operations which operate twenty-four hours per day, seven days a week, with daily advances of several hundred feet, the savings in transport and installation time can be significant.
The hinged mine stopping requires less sealing material than other mine stoppings. The hinged mine stopping of the present invention only requires sealing about its perimeter, and depending on the embodiment, between adjacent upper panel sections.
Accordingly, it is a principal object of the invention to provide a hinged mine stopping adapted for being disposed in a V-shape in a mine passageway to provide higher load ratings than straight walls made from comparable materials.
It is another object of the invention to lower the installation time for a mine stopping by constructing the stopping from elongated hinged panels.
It is a further object of the invention to improve transport efficiency of mine stopping into a mine through a low profile hinged mine stopping.
Still another object of the invention is to provide a mine stopping for improved mine ventilation which is both V-shaped for increased load resistance and adjustable in height to adapt to the size of air passages in the mine.
It is an object of the invention to provide improved elements and arrangements thereof for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.